She had her home town burnt down and she was nearly killed by a seven foot tall tranny with a 12 foot long sword. That would preeeety fairly effectively cover the trauma angle solidly. This is without the falling from a cliff and seeing all the stuff inside the reactor. Also the general mind fuck that would happen with your mind when you consider FF7 from her perspective (Cloud knowing shit there is no way he should know as far as she is aware and she is travelling with him for that long not knowing until disc 3. The big stuff inside the crater mid game visibly shakes her and bothers her in general worse than the return to Nibelheim did.
Life happens and not all games need to be an exercise in pure escapism. Tifa being vaguely realistic is appealling to the psychology student in me and gives FF7 some impact far stronger than the game really deserves.
As for Advent Children plot, well besides the obvious, pretty much everyone there that got character development regressed back to mid game or so because apparently writing new character development is beyond the scope of FF7 spin offs when they can have rehash plot as a cardboard backdrop to their shiny choreographed digital actors. (Advent Children is pure escapism and has zero impact)
Can't speak for Crisis Core plot or Vincent May Cry plot either, I have completely written off even contemplating VMC plot trainwreck and CC from my understanding incorporates the trainwreck, might do a better job of it, but meh to that I say.
And of course, ultimately
True Art is AngstyEdit - Oh and of course I never said PTSD made you intelligent and not carry the
Idiot Ball whenever the plot demands.
Edit 2 - Post Traumatic Stress Disorder.
Edit 3 - For more fun times I was bored and hit up the Wiki for PTSD. Here is list of symptoms hijacked from the DSM-IV
A. Exposure to a traumatic event
B. Persistent reexperience (e.g. flashbacks, nightmares)
C. Persistent avoidance of stimuli associated with the trauma (e.g. inability to talk about things even related to the experience. Avoidance of things and discussions that trigger flashbacks and reexperiencing symptoms. Fear of losing control.)
D. Persistent symptoms of increased arousal (e.g. difficulty falling or staying asleep, anger and hypervigilance )
E. Duration of symptoms more than 1 month
F. Significant impairment in social, occupational, or other important areas of functioning (e.g. problems with work and relationships.)
I can fairly comfortabley note 5/6 symptoms for Tifa just from memory. She still functions socially fairly acceptabley until pushed however. The inability to function is normally what you flag as making somethign a full blown disorder though.